math.h

Martin Thomas wrote:
> Kim Madsen wrote:
>> Hi
>> Why does it not work.
>>
>> float logEx,dew_point,mellem = log10(h);
>>   logEx=0.66077+7.5*t/(237.3+t)+(mellem-2);
>>   dew_point = (logEx - 0.66077)*237.3/(0.66077+7.5-logEx);
>>   return dew_point;
>>
>> I got a linker error.?
>
> Not enough information. Which error? Option -lm used for linking?

It is undefine reference to  'log10'
This is the arm-gnu I am using.

It is the right answer, a change in the makefile, adding -lm
and it work.
thx